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Accepted
Samir Sabri
Asked: 2012-02-11 23:05:28 +0800 CST

How to increase brightness in smaller steps?

  • 772

Is there a way to adjust lighting step ? I have Lenovo L520, and Fn + Light Up or Down adjusts by 20%, how can I adjust the step to 10% ? it will help me fine tune lighting at my dark room.

backlight brightness

17 Answers

  1. Best Answer

    Install xbacklight by opening a terminal with Ctrl+Alt+T shortcut and type this:

    sudo apt-get install xbacklight

    then after installation, type these commands in terminal:

    xbacklight = 10
xbacklight = 20
xbacklight = 5

    this may help.

    • 18

  2. There is a file in Ubuntu which stores numerical integer value of brightness. you will find 3 files in the directory /sys/class/backlight/<VGA>directory replace directory with intel_backlight for intel cards.

    You will find the max brightness value in max_brightness file and according to that value set the brightness in brightness file.

    • 9

  3. For Xubuntu LTS

    Firstly, install xbacklight

    $ sudo apt install xbacklight

    Secondly, check whether you have control over the backlight.

    $ xbacklight -1
$ xbacklight +5

    Should these commands result in a No outputs have backlight property error, then follow these remediating steps before proceeding.

    Once xbacklight -1 and xbacklight +1 work from the command line, proceed with assigning these commands to respectively the XF86MonBrightnessDown and XF86MonBrightnessUp keys. This is done by hitting those keys when asked by the Settings → Keyboard → Application Shortcuts application.

    Finally, reboot for these changes to take effect.

    Keyboard settings

    • 7

  4. You can install xcalib and then type the command: 

    xcalib -co 50 -a

    Use xcalib -h for help regarding it's options.

    • 3

  5. As Colin Ian King said, the levels of brightness are hardware related.

    Some laptop screens have 8 levels of brightness and new ones have 16 levels.

    On Windows OSes you can change the levels with 1% steps, but they will be rounded to the nearest hardware level. It depends on the screen type.

    • 3

  6. My solution was to install 'xbacklight'

    Then I created keyboard shortcuts such as

    • ctrlshift+ with command xbacklight +5
    • ctrlshift- with command xbacklight -5

    So when you use those shortcuts they call the related command however I could not replace the system inbuilt brightness buttons to use these commands You can use almost any keyboard shortcut button combination you like with xbacklight.

    • 2

  7. On Ubuntu 16.04, with Intel onchip graphics (i5) under LXQt, it is sufficient to assign xbacklight commands to the brightness function keys XF86MonBrightness(Down|Up) using the global key shortcut settings. These seem to override the defaults even if /sys/module/video/parameters/brightness_switch_enabled is set to Y, while the original functionality on virtual terminals is retained. LXQt global key shortcut configuration with xbacklight commands

    An alternative to the original xbacklight would be acpilight, but unfortunately this isn't available as Ubuntu package. As it doesn't depend on an X display running, you can also associate it with ACPI button events and use it from the console. Additionally it can store the current brightness on shutdown and restore it on boot.

    • 2

  8. For me xbacklight did not work (EDIT: probably because I did not reboot my machine), therefore I created my own script which uses the built-in gsd-backlight-helper.

    This script uses smaller steps, especially when the screen is quite dark already.

    Step 0: check if it works (optional)

    To see if it works you could try:

    pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-brightness

    This should output a number.

    Step 1: save script

    Save the following script in an .sh file, for instance in /home/me/scripts/brightness.sh.

    #!/bin/bash

max=$(pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-max-brightness)
cur=$(pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-brightness)
if [ $(($max/$cur)) -ge 25 ]
then
    step=$((max/300+1))
else if [ $(($max/$cur)) -ge 5 ]
    then
        step=$((max/50+1))
    else
        step=$((max/20+1))
    fi
fi
case "$1"
in
+) new=$((cur+step));;
-) new=$((cur-step));;
esac
pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness $new

    Step 2: assign shortcuts

    Open Keyboard Shortcuts from the Settings menu and assign shortcuts:

    name:     Darker
command:  sh /home/me/scripts/brightness.sh -
shortcut: Super + F5

name:     Brighter
command:  sh /home/me/scripts/brightness.sh +
shortcut: Super + F6
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  9. The brightness levels are generally under ACPI control with the levels defined in firmware. For example the ACPI control method _BCL "Query List of Brightness Control Levels Supported" informs the kernel how many brightness levels are supported. You can't realistically change this.

    • 1

  10. In my case (Lenovo T500) the problem is, that the brightness regulating key-press is applied twice - once by using the Xwindows, but also independently in the lower level, by kernel's graphic driver itself. So the brightness steps are twice as big as usual.

    The working solution is to deny the low-level functionality, by adding this line to /etc/rc.local (just before the line with 'exit 0'):

    echo -n 0 > /sys/module/video/parameters/brightness_switch_enabled

    This way it will perfectly work in logged-in X session, unfortunately it will remove the key-press brightness regulation functionality in all other cases (console terminal, X login screen etc).

    • 1